'\"macro stdmacro
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.TH PMFETCHARCHIVE 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmFetchArchive\f1, \- get performance metric values directly from archives
.SH "C SYNOPSIS"
.ft 3
.ad l
.hy 0
#include <pcp/pmapi.h>
.sp
int pmFetchArchive(pmResult **\fIresult\fP);
.sp
cc ... \-lpcp
.hy
.ad
.ft 1
.SH DESCRIPTION
The
.B pmFetchArchive
API is a variant of the
.BR pmFetch (3)
interface that may only be used when the current
Performance Metrics Application Programming Interface (PMAPI)
context is associated with a set of archives.
.PP
The
.I result
is instantiated with all of the metrics (and instances)
from the next archive record,
consequently there is no notion of a list of desired metrics,
and the instance profile of the PMAPI context is ignored.
.PP
.B pmFetchArchive
may return a
.I result
in which
.I numpmid
is zero.
This is a
.I <mark>
record that indicates a temporal discontinuity in the time series
of performance metrics.
This can happen at the boundary between archives in a set or if
the archive associated with the current PMAPI context was created
using
.BR pmlogextract (1)
to concatenate two or more PCP archives, and the
.I <mark>
record marks a point in time between the end of one input archive and
the start of the next input archive.
.PP
It is expected that
.B pmFetchArchive
will be used to create utilities that scan sets of archives,
while the more common access to the archives would be via the
.B pmFetch
interface.
.PP
To skip records within the set of archives, use
.BR pmSetMode (3)
to change the collection time within the current
PMAPI context, then call either
.B pmFetchArchive
.PP
Note that the
.I result
returned by
.B pmFetchArchive
is dynamically allocated, and
must be released using
.BR pmFreeResult (3),
but not
.BR free (3).
See
.BR pmFetch (3),
and
.BR pmFreeResult (3)
for further details.
.PP
.B pmFetchArchive
returns zero on success.
.SH DIAGNOSTICS
.IP \f3PM_ERR_NOTARCHIVE\f1
the current PMAPI context is not associated with a set of archives
.SH COMPATIBILITY
Prior to PCP 7.0 the
.I timestamp
field in the \f(CRpmResult\fP struct was a \f(CRstruct timeval\fP.
To support PMAPI transition, the old interface and semantics can be
used if applications are recompiled with
.BR \-DPMAPI_VERSION=2 .
.PP
For a time in PCP 6.x there was a
routine with the same semantics as the current
.B pmFetchArchive
called
.BR pmFetchHighResArchive ,
and a struct with the same definition as the current
\f(CRpmResult\fP struct called
\f(CRpmResultHighRes\fP,
although both are now deprecated and compile-time support for
.B pmFetchHighResArchive
and \f(CRpmResultHighRes\fP will be removed in a future release.
.SH SEE ALSO
.BR PMAPI (3),
.BR pmFetch (3),
.BR pmFreeResult (3),
.BR pmNewContext (3),
.BR pmSetMode (3)
and
.BR pmTrimNameSpace (3).
